Remove unused variable and check

Author: Cuda-Chen

virtio-snd.c

@@ -296,6 +296,12 @@ typedef struct {
     uint32_t stream_id;
 } vsnd_stream_sel_t;
 
+typedef struct {
+    uint32_t addr;
+    uint32_t len;
+    struct list_head q;
+} vsnd_buf_queue_node_t;
+
 /* hold the settings of each stream */
 typedef struct {
     virtio_snd_jack_info_t j;
@@ -307,6 +313,8 @@ typedef struct {
 
     // PCM frame ring buffer
     virtio_snd_ring_buffer_t ring;
+    // PCM frame doubly-ended queue
+    vsnd_buf_queue_node_t buf;
 
     // playback control
     vsnd_stream_sel_t v;
@@ -921,7 +929,6 @@ static int virtio_snd_tx_desc_handler(virtio_snd_state_t *vsnd,
     virtq_desc_queue_node_t *node;
     struct list_head q;
     INIT_LIST_HEAD(&q);
-    assert(list_empty(&q));
 
     /* Collect the descriptors */
     int cnt = 0;
@@ -975,13 +982,10 @@ static int virtio_snd_tx_desc_handler(virtio_snd_state_t *vsnd,
     }
 
     /* Tear down the descriptor list and free space. */
-    /* TODO: remove this part as we are going to use ring buffer */
-    idx = 0;
     virtq_desc_queue_node_t *tmp = NULL;
     list_for_each_entry_safe (node, tmp, &q, q) {
         list_del(&node->q);
         free(node);
-        idx++;
     }
 
     return 0;